Fastener apparatus of this particular kind are useful in fastening together two panels subject to high separation forces and to limited lateral displacement relative to each other. One example of such a fastener apparatus is disclosed in U.S. Pat. No. 3,081,809, issued to F. W. Rohe. The disclosed apparatus includes a nut having a threaded bore for receiving a conventional bolt and a generally cylindrical retainer for loosely supporting the nut in a prescribed position while permitting the nut to move by limited amounts in directions both perpendicular and parallel to the nut's longitudinal axis. A transverse hole is formed in the retainer, aligned with the nut's threaded bore, to guide the bolt into threaded engagement with the nut.
The retainer is sized to slide into a cylindrical bore formed in one of the panels to a position where the retainer's transverse hole aligns with a transverse hole formed in the panel, to permit the bolt to threadedly engage the nut.
Although the barrel nut fastener apparatus described briefly above has proven to be generally satisfactory, it is nevertheless subject to certain drawbacks. For example, only a small portion of the nut extends beyond the perimeter of the transverse hole formed in the retainer, which guides the bolt to the nut. Consequently, very high compressive stresses can arise at the interface between the nut and the retainer, which can sometimes cause the nut to deform.
Further the retainer can sometimes rotate within the cylindrical bore of the panel, about the retainer's longitudinal axis, such that the nut's longitudinal axis, is no longer parallel with the expected longitudinal axis of the bolt. Consequently, cross-threading of the bolt into the nut can sometimes occur. Prior art devices have attempted to solve this particular alignment problem by using spring clips or similar items. While such have proven workable in certain applications, there remains a need for improvement in the alignment and retention feature for the nut portion of the fastener apparatus. Known prior art devices employ a separate spring clip or like element, and assembly with the fastener apparatus is often difficult and unreliable in the field.
It should, therefore, be appreciated that there is a need for a mechanism which in a single-piece assembly permits reliable alignment and retention of the nut with the bolt hole in the panel and thus ensures that the retainer will not rotate about its longitudinal axis, to a point where cross-threading of the bolt into the nut can occur. The present invention fulfills this need.